<!DOCTYPE html>
<html>
<head>
<style>
span { color: red }
:default + span { color: green }
span.reverse { color: green }
:default + span.reverse { color: red }
input { display: none }
</style>
</head>
<body>
<form>
<div>
  <input type="radio" checked="checked" id="foo">
  <span>There should be no red.</span>
</div>
<div>
  <input checked="checked"><span class="reverse">There should be no red.</span>
</div>
</form>
</body>
</html>
